Amyotrophic lateral sclerosis (ALS or Lou Gehrig's disease) is neurodegenerative disorder characterized by the progressive destruction of large motor neurons in the spinal cord and brain. Approximately 10% of ALS-afflicted individuals having the inherited (familial) form of the disease (FALS) display tight genetic linkage between the disorder and a gene encoding a cytosolic Cu/Zn-binding superoxide dismutase (SOD1). We desire to correlate ALS misfunction withCu/ZnSOD structure via crystallographic analysis of human SOD mutants found in FALS patients.